1. Field of the Invention
The present invention relates to: an ion generating apparatus provided with an ion detector for detecting ions in air; and a judgment method for presence or absence of ions.
2. Description of the Related Art
In recent years, techniques for cleaning air in a residential space by virtue of positive and/or negative ions are used widely. For example, in ion generating apparatuses including air cleaners, an ion generator generating positive and negative ions is arranged in the middle of the internal ventilation flue. Then, the generated ions are released to the external space together with air.
In a space where ions have been released, when the concentration of ions is 1,000 to 2,000 ions/cm3 or the like, a significant disinfection effect is obtained against bacteria such as serratia bacteria and bacillus bacteria. Further, ions in air inactivate airborne particles and denature odor components. Thus, air is cleaned in the entire residential space.
In standard ion generators providing the above-mentioned effect, a driving voltage of high-voltage alternating current is applied between a needle electrode and an opposite electrodes or alternatively between a discharge electrode and a dielectric electrode so that corona discharge is generated and hence positive and negative ions is generated. When a plurality of ion generators are employed, the concentration of ions in air is enhanced.
On the other hand, during long term operation of ion generators, the discharge electrode is worn out by spatter evaporation associated with corona discharge or alternatively the foreign substances such as chemical substances and dust are adhered to and accumulated on the discharge electrode. In such cases, the rate of ion generation decreases unavoidably. Then, in order that the user should be notified that maintenance is necessary for the ion generator, the presence or absence of ions in air need be judged.
In such a situation, for example, Japanese Patent Application Laid-Open No. 2007-114177 (Patent Document 1, hereinafter) discloses an ion detecting device and an ion generating apparatus in which a collecting electrode collecting ions in air is provided and the presence or absence of ions is detected (judged) on the basis of a change in the potential of the collecting electrode generated when ion generating operation is started (or when ion generating operation is stopped).